/Engine/Source/Editor/UnrealEd/Public/EditorModeManager.h
Sets the host for toolkits created via modes from this mode manager (can only be called once)
void SetToolkitHost ( [TSharedRef](API\Runtime\Core\Templates\TSharedRef)< [IToolkitHost](API\Editor\EditorFramework\Toolkits\IToolkitHost) > Host )